1. Field of the Invention
The invention relates to testing systems, and more particularly, to a testing system for Field Emission Flat Panel Display (FEFPD) devices.
2. Description of Related Art
Flat panel displays, and specifically Field Emission Flat Panel Displays (FEFPDs), are technologically viable alternatives to cathode ray tubes (CRTs) for display of electronic information. They provide several advantages over CRTs, including smaller weight and size and lower power consumption. However, some manufacturing problems, such as the capability to test their expected performance, often make them more expensive than typical CRTs.
FIG. 1 shows a magnified cross-section schematic of a typical FEFPD 20. A substrate 11 is manufactured with several microscopic conical structures or Field Emitter (FE) cathodes 13. An electrode gate layer 15 confronts the substrate 11 and is provided with holes 17 just at the tip of the FE cathodes 13. The gate layer 15 is biased to a relatively high voltage (on the order of a few hundred of volts), causing the field emission and acceleration of electrons 19 located at the tip of the FE cathodes 13. The cathodes 13 are also biased to a positive voltage to control the amount of electrons emitted once the gate layer 15 enables their flow. Electrons 19 impact the inner surface 21 of a phosphorous-coated plate 23. Plate 23 is disposed in close proximity to gate layer 15, while the region between the substrate 11 and plate 23 is held under vacuum conditions to facilitate the emission process.
The impact of electrons 19 on the phosphorous-coated plate 23 causes photon emission at the outer surface 25 of plate 23, as indicated by arrows 27. By modulating an arrangement of row and column of FE pixels, a controlled light image can be generated.
FIG. 2 shows schematically the pixel arrangement of FEFPD 20. The panel is divided into a set of columns 31 and rows 33. One of these sets electrically comprises the FE cathode substrate while the other set comprises the FE gates. Pixels 39 are selectively activated by applying a voltage to the row and column intersection via a set of column and row drivers (35 and 37, respectively). Each pixel 39 contains more than one FE cathode, and a typical pixel arrangement contains an array of about 10.times.10 cathodes electrically connected in parallel. This redundant amount of cathode emitters increases the probability that the pixel display performance will be acceptable even with a few of the cathodes not operating properly. One of the purposes of this invention is to assess the amount of FEs that are operative for each pixel 39 by measuring the emission uniformity of all the pixels of the display.
It is recognized that for replacing CRTs in consumer applications such as TVs and computers, FEFPD manufacturing costs, which include costs of inspection during the manufacturing process to insure quality control and a functional product, must be reduced.